4. Because you care about her

There is a reason you are dating her in the first place. You have a terrible way of showing it, but you really do care about her. If you didn’t care, then the one-night stand would have been much more. You do love her and if you didn’t, you wouldn’t be feeling this guilty. Cheating was bad enough, so the last thing you want to do is hurt her again. Telling her will crush her. Make it up to her by being a better boyfriend than before you cheated and actually show her how much she means to you.